Soustd-detectiosr tsaitfustg device



Jan. 17, 1928. 1,656,533

L. H. RICHMOND SOUND DETECTION TRAINING DEVICE Filed Oct. 4. 1926 2Sheets-Sheet 1 Jan. 17, 1928. 1,656,533

: L. H. RICHMOND SOUND DETECTION TRAINING DEVICE Filed Oct. 4. 1926 2Sheets-Sneet 2 Patented Jan. 17, 1928.

UNITED STATES LEON H. memro'nix OF Fem H. G. WRiGHT, NEW YORK.

J V i. i SOUND-DETECTION TRAINING DEVICE.

V iilyention relgite s to a 1 J .e peiatu er he t st eehav immi entindividual s hinz iirel sense orthedegree o equality of spl n gldetection of one ear in l "u' it. Q. LL. 1 .i':'/,- i st. of. y i ie e5s tepmwfi: when; PP? T B;F- 1% u a 9 2 tr em siv 9 9m iio e e. is-sees? e-sach ar .Qf.. e s i ri t e. epneie being ,e etiet di t h e i9. tsee et. y. 0.. per t t same fill .P. ..9..% a: sound is nearerone'fof the seryeris ears ,...a -th. rs. nd hs 'g he qhsrw ay espiiiidep n t y re et the 9PM. ec eiis appar tu illdfi fllQ i nflQY lg ni h fi sewqe iesnsha s ti 5. L AJ B. ashes jiidginent, as a resiit of 1sbinn n ral sense alone, the sound is reaching both ears simultaneously.H l: a u

Another object of in'iie'ntion is to provideth e apparatus withindicating and reco r ing devices iivli'rehy tl e degree of accuracy ofthe ohs eiv'rs observ itioiis inst y be definitely det'etinined in or erto test and tfaiii his ability iii this particulr ty e of soiinddetection. e v

To this end I propose to pi'ovide an apierzi t iiscoinprisingu source znd a inoving To zi ccoinplish iZI lIS IJt-I IIFPIQY "a hydrophone iteach end of and suhrnerged in a tank of water, with h eomiect'ionto'tlie eoi i-s'fioiiding ear (if the obe's-m movement by the observerof the tank coir taining tlie hydi ophone'sivith relation to theinstriictofis' setting of the soiii'ce of sound, enables the observer tobring the source inidiiiify bet'i'ven the two hydfoplioiies by nieans ofhis binaiirz il seiise ivitlioiitthe aid of iii's io'n. The degree ofaceiirzicy mammph shi g' this is a comprehensive test of hishiiiiiu'ra'l observation ability.

With the foregoing :iiid other objects in View, iiiy invention consistsin the coinbinatidn of parts and in the details of consti-iicrich setforth hereinafter, cel rtziin embodiin nts'threofbeing illiis ted in theaccoinpanying drawings, in which: A Y Fig.1 is a view in perspective andpartly in section of the mechanical elements of my device. Y I

2 is a diagraininatical illustration of theelectiical Wiring system. 7

3 is a diagrainniatical sketch of a modified form of the system.

Fig. 4 is a diagraininnticul view in per- Tlie geei h pf the device fofrecording the movements i the se line,

efg'ed in the iifl- '.he' tziiil-; is iji f e'r- 11;: h loi'igfs'litThis is for the of pfrefeiit iiifi the Water in th evlzin'k f r'oiii'jsplfisliiiig oiit when the tank is iiioi 'e d rzi The li'iih isiilled'iv'ith Water to wi giiin zi 'jp'roxiiniitcly an inch from thetop.The tii'iik is nioiiiit ed on it sinzill foLir-wheel 'tri'ic'k hiii ing' wheels 6 which i'oil on a truck 9, Which piir 'ziliel to the t-ng't'ho'i' the 'ooiz. A (Eib e 7' is iittaclied to the snizill truck tind to'a' pa Icy on the obseri'e'r's' side of thesppariitiis'insii'ch a mannerthat the tiirning' 0f the lihdh S will inove the truck and conseqlien'tly the tank in either direction desired. Atones'ide of the tllllkis fastened an if)- r'iglit sheet 12 of sound absorbent material \X hichprevents the observer from seeing the relative setting of the source ofsound and the hy'dr'o'jihones. It is also conveniently used to ca'irythe Yzirious electrical instruiiients nihking up the electricalcircuits. I

There is a similar track 17 close to and parallel with he first track 9.This tifack is zilso provided with a truck 15 having Wheels 16 and a.pulley l8 and cable 18' operated by the knob 19. All of this is tihly'co'veifed iiitli tte'ji oi sheet lntfilgll hay ill) . unde rneath itina direction atright A diagram of ,the' elect located on the instructorsor recorders side of the apparatusl'in such amanner that-it may beoperated without the observer seeing such operation. The truck 15 has anupright piece 14 which carriesthearm 13 to which is attached a suitablesource of sound. The present source of sound in use is a very fine jetof air bubbles which sues from a nozzle attached to th'e truck. A heavyarm 20. carryin a pencil 21 is hinged to the truck; 15 directly underthe arm 13 carrying thesourcle of sound/TA similar arm carrying "a?pencil 11" is hinged to the truck 5 carrying thetank and is attached ata pointmidw'ay between'tlre two 'hyd'rophones which form the base line.The weightof the arms issufiicienttocause the pencils record" 'tlie'settings on" the record sheet'22. 1

This apparatus is so .lfiOllIltQd on 'a'ta'ljle that thereis groomforpaperi to be drawn to the movement 'ofthe a rical circuitf'is shownin Fig.2. "This .circuitjs especially designed. toavoid.op'erating'troubles and to supply the 'same amount 'of energy'current through each hydrophon'e. ,The circuit "of the energizingcurrent (direct current) 15 from the battery 23, through. onehydrophone'l, througha milliammeter 3', a'heavy iron-cored choke coil4',through the other hydrophone 2,1'and back "to the battery 23. Asingle pole single-throw switch 28' in the circuit enables themaking'and breaking of 'the circuit. The alternating current componentoriginated. by the action of the hydrophone is, from the hydrophone 1,through a A microfa'rad condenser 24 through one earphone which isconnected to the terminals 28 and 29, through the battery 23 and back tothe hydrophone 1. The path of the alternating current, originating inthe other hydrophone 2, is exactly similar except that it has nobattery. The function of the choke coil is to prevent the alternatingcurrent component arising in one hydrophone from getting into thealternating current circuit of the other hydrophone. In this anner crosstalk is prevented. The function of the two condensers 24 and 25 is torevent battery current passing'through t e earphones. Each earphone isshunted by its corresponding variable resistance 26 or 27,

by the use of which the intensity of sound may be controlled.

The whole device is on a table measuring 3 x 1%. Its height from thetable, including the sheet of celotex, is 2 The total weight, withoutthe water, is approximately 100 pounds. In addition to the device asdescribed, there must be provided some source of air pressure if an airbubble source of noise is to be used. 7

There are no special precautions to "be Theoperation'isvery simple. Theat server takes his position behind the apparatu's arid turns on -the'battery current. This current has" a normal value Which', i{ exceeded,"as shown by 1 the reading of the inilliammeter, is .bi"oiight 'down bysmartly iap ingth-mnk, thus npacking the hydrophone The training thenproceeds i by" the instructor moving the {source of sound to anyposition and the bbs'erver moving the 'ftank-untilhis' binauralsenseinforms him that theisound is'midway between the hydrophones?" A, greatmany i variations of" this ispossibley j Y "he apparatus for recordingthe -move'- ments of thebaseline as an observer follows a moving sourcehas'not yet beenadded to the device. "Itconsists 'of 'asma'lt motorgeared down to tum a roll ata slow and constant's'peed." F rem a' supplyroll paper .is led over the top of the table but "under "the apparatusincluding the two recording pencils to the motor-turned roll. Thefpenoils mark the path'of their movements as the paper Pa s s underthem-J The time element is determined y the t f speed atrwhic'h.

the roll turns and its diameter. If a more refined time measurement isneeded, it can be done by having a pendulum'actuate'a coil so thateachswing will cause a spark to pass thru the paper when proper arrangementsare made 'for it. 5

.Let the' table in the accompanying figure represent the table 'shown inFig. 1, Let the paper 11, Fig. 1 be replaced bya continuous sheet ofpaper, B supplied from a roll A and moved along by being rolled on theroller C. The roller C is'driven by a constant speed motor E andsuitable gears D. Resting on the paper are the two pencils 10 and 20,(also shown in'Fig. 1). These pencils should be of different colors. Nowas the paper moves at right angles to the movements of the pencils,there. will be a record impressed on it which will show the relativemovements of the two pencils. As the pencils are rigidly attached to thebase-' line, the base line movements are recorded. The relativemovements can be converted into time movements by calibrating theapparatus to determine how fast the paper moves.

If more refined time measurements are desired they may be obtained asfollows:

Let G be a sharp pointed insulated terminal mounted flush with thetable. Immediately above it but separated by a distance just suflicientto allow paper to pass is another insulated electrode G. To eachelectrode is connected a battery L and in the circuit is a pendulum witha bob M passing through a cup of mercury K. The pendulum beats toregular time intervals and these time intervals are registered on thepaper by a spark passing between G and H thus producing a characteristicmark on the paper. The pendulum may be calibrated to as high a degree ofprecision as necessary.

A different arrangement of the tank and the path of the source of soundwill permit of the moving of the base line or the source of sound so asto give a maximum effect as well as a binaural efi'ect. How this is donecan be readily seen by Figure 3, in which ABCD is the outline of thetank, SS is the path of the source of sound, and H and H are thehydrophones. It is seen that as the source moves towards the midpoint 0,it imparts greater energy to the hydrophones, thus increasing theintensity of the sound. In order to get this to be the greatest ener yin each hydrophone at the midpoint of the path, it is necessary to turnthe hydrophones at some angles such as shown by the dotted lines. Theeffect of this is to turn the face of the hydrophone away from thesource when it is near the hydrophone, thus causing the hydrophone topick up less energy. The correct angle could be determined byexperiment.

Having thus described my invention, I claim:

1, In a sound detection apparatus, a single source of sound, a pair ofsound responsive members and means attached thereto to permit of auralreception by an observer, means for moving said source of sound to varythe relative position thereof with respect to the two sound responsivemembers, and independent means operable by said observer for moving saidsound responsive members equidistantly from said source of sound inaccordance with his binaural observations.

2. In a sound detection apparatus, a single source of sound, a pair ofsound responsive members and means attached thereto to permit of auralreception by an observer, means for moving said source of sound,visually unobserved by said observer, to vary the relative positionthereof with respect to the two sound responsive members, andindependent means operable by said observer for moving said soundresponsive members equidistantly from said source of sound inaccordancewith his binaural observations, and means for recording thevarious settings for the purpose of testing the degree of the observersaccuracy.

In testimony whereof I aflix my si nature.

LEON H. RICHM ND.

